What if the leather inside the unsealed bag also falls out?

You should say "ink back printing". Usually, there are two situations. First, it is very common to fall off naturally because it is not firmly adhered. In this case, just wipe the glue on the back of the leather and stick it with double-sided tape. But it is very likely that the wrong ink (non-ink-returning ink) is used, which causes the seal surface to deform and fall off. In this case, it is necessary to re-engrave the seal or re-engrave the seal cover. In addition, it is necessary to replace the inkpad that was not oiled correctly before (there is a built-in inkpad).